ColourSchemes enum requires loading of every color scheme

Right now JalviewColourScheme loads every possible class as part of its initialization. wouldn't it better to do this in a lazy fashion? Just declare the value as the name, and then initialize upon getSchemeClass() calling. Registration in ColourSchemes, I think, could also be done lazily by using the enum constant's name instead of the ColourScheme's name (which are by definition the same). Looks like mostly the name is checked anyway,

Maybe not worth the trouble.